There are two ways you know you've entered the Kidz Field. First, a smiling woman in a yellow security vest says "Smile ... now!" as you go under the arch into the field. Secondly, there is a sudden outbreak of men of a certain age lying sleeping in the sun, or surreptitiously reading the newspaper.

Any dad will tell you that sleeping men of a certain age, or men reading newspapers in huddled groups, is a sure sign of kids securely at play somewhere nearby. This is the normal behaviour of the exhausted male when his offspring are being entertained by someone else - a chance to catch up on sleep, or the news. While the mothers watch their fledglings indulgently, the men wallow in temporary escape. They could just as easily have called it Dadz Field.

Just past the entrance to the Kidz Field there is a gigantic wall on which kids can paint, under the supervision of someone called "Hugh Jart" (geddit?), and leave messages like "Jack thought Kings of Leon were great" (which is odd, because I don't think anyone else did), "Black Eyed Peas Rool" and the rather un-Glastonbury "paint over this and you're dead".

Once inside the fields, there are a range of activities, including the Animal Train, a "percussive sculpture" which looks like a Dr Seuss vision and which a bunch of kids were banging away on merrily; hopefully, they will show the same impulse the next time they see a Tracey Emin. There is a circus tent offering shows like Dude, Where's My Teddy Bear, Puck's Bottom, and Foolhardy Folk, who sound like druids but are in fact "masters of slapstick." There's a story-telling tent, and a DJ playing Johnny Cash standing on a trolley painted in ladybird colours.

The overwhelming vibe is middle-class urban. For every hippy parent with locks and tattoos, there are half a dozen sensibly dressed women sitting on sensible picnic rugs with sensible coolboxes. These are women who think that the Kidz Field's baby yoga must have some merit, and who presumably met their spouses while finding themselves in India. And just as with every 'country fayre' in a London park, there is an enormous queue for the facepainting. If you're not a parent, you won't understand the fear that a queue for facepainting normally engenders, but the Glastonbury magic had worked its effect. The kids in the queue actually looked like they were willing to wait their turn.

The most impressive thing in the Kidz Field is the crafts tent. This was absolutely crammed with kids making things, drawing things, painting things and modelling things. I don't know, and forgot to ask, what the qualifications of the people doing these things with the kids were, but the general description 'miracle worker' might be appropriate. Call it the Glastonbury vibe, call it the ley lines, call it whatever you want - but for that many kids to be occupied in a meaningful way, something magical must have happened. It certainly wasn't the national curriculum.

We left the Kidz Field feeling spiritually refreshed. The dads still slumbered quietly, the mums put things in and took things out of picnic boxes, the children played merrily. Outside, the Valkyries were riding out of the Pyramid stage, presumably on their way to get their faces painted.